Glue drying apparatus and method



Jun 12, 195 A. H. ZEIGLER ETAL GLUE DRYING APPARATUS AND METHOD 2Sheets-Sheet 1 Filed Sept. 25 1947 June 12, 1951 A. H. ZEIGLER EI'ALGLUE DRYING APPARATUS AND METHOD 2 Sheets-Sheet 2 Filed Sept. 25, 194?Patented June 12, 1951 GLUE DRYING APPARATUS AND METHOD Albert H.Zeigler, Kenilworth, and Charles M. Harris, J13, Chicago, 111.,assignors to Armour and Company, Chicago, 111., a corporation ofIllinois Application September 25, 1947, Serial No. 776,051

Claims. 1

This invention relates to a gelatin drying apparatus and method. Theinvention is particularly useful in the drying of animal glue, vegetableglue, edible gelatine, and other forms of gelatin. It will be obviousthat the process is applicable also to the treatment of other types oftacky material. For the purpose of illustrating the invention and forclarity, the process and apparatus will be described specifically inconnection with the drying of glues.

In the drying of glues, great difficulty is experienced in the formingof a sheet of glue and the conveying of the same through a drier. If thesheet is dried extensively, it becomes brittle and cannot be handledeffectively in the apparatus. On the other hand, if the sheet isflexible so that it can be effectively handled, the sheet is tacky andtends to cling to the conveyor mechanism upon which it is passed througha drier.

' In the handling of animal glue, including edible gelatin, theresulting glue sheet is unusually tacky and effective handling of thesheet is extremely difiicult.

An object of the present invention is toprovide apparatus and a methodfor the forming of gelatin sheets in large volume, while at the sametime efiectivel-y drying the sheets without causing their adherence tothe apparatus. A further object is to provide a means and method wherebygelatin can be formed continuously upon a roll and drawn away therefromupon conveyor" apparatus with a continuous gelatin sheet renderednon-adherent tothe apparatus upon which it is carried away. Yet anotherobject is toprovide means whereby the gelatin which is fed to the dryingapparatus may be maintained uniform in composition by means of recyclingthe same. Yet another object is to provide mechanism for the handling ofa glue film of relatively thick proportions upon a drying drum, togetherwith means for maintaining the film evenly upon the roll. A stillfurther object is to provide mechanismwhereby the dry side of the filmformed upon the drying roll can be brought to rest upon the conveyor,thusto reduce the tendency of the filmor sheet to adhere to theconveyor. A still further object is to provide means whereby the objectis to provide improved drying means for producing a dry glue sheetreadily broken in a fragmentation machine. Other specific objects andadvantages will appear as the specification proceeds.

The invention is illustrated,- in a single em bodiment, by theaccompanying drawings, in which I Figure 1 is a broken longitudinalsectional new of apparatus embodying our invention; Fig. '2, a top planView of a portion of the glue sheet withdrawn from the drying roll; Fig.3, a greatly enlarged sectional detail view, the section being taken asindicated at line 3-3 of Fig. 2; Fig. 4, an enlarged sectional detailview of a portion of the drying roll, and glue applying and removalmechanism; and Fig. 5, a perspective view of the means employed forapplying a glue film to the drying roll.

In the illustration given, It designates a drying roll having closedends and mounted upon a hollow shaft It provided with ports [2 to whichsteam or other heating fluid may be admitted to heat the chamber withinthe roll. The roll is rotated by the usual motor-driven gear mecha-'-nism (not shown).

The roll it is preferably of large diameter, as, for example, nine feetor more. Above the roll it] is mounted a hood it with means for drawingoff the vapors that are admitted during the drying of the film upon theroll.

Any suitable means for applying glue to the roll 10 may be employed. Inthe illustration given, we provide a container [-4 on" the righthandside of the roller, as illustrated in Figs. 1 and 4, and supportedwithin the container is a driven roller l5 for applying a film It ofglue to the roll Hi. The interior of the roll 15 is hollow, and thehollow pipe ll admits any heating fluid desired to the interior of theroll 15. In the illustration given, It designates a Valve-controlledsteam pipe communicating with pipe [1, and 1-9 indicates avalve-controlled water pipe communicating with pipe ll.

Glue is supplied from a reservoir 20 heated by a steampipe it through avalve-controlled pipe 22 to the container it. A valve-controlledoverflow pipe 23 within the container i l" main tains the glue bodytherein at a desired level and permits the bypassing of glue'irom thecontainer I4 to the vessel 24' from which it is pumped through the valvecontrolled pipe 25 by means" of thepump it back to the reservoir 2! Itis found that in the application of glue to'the roll It; a portion ofthe glue, after'meeting' the roll In and after being subjected to theheat thereof, rolls back into the container !4. This return of gluewhich has been subjected to contact with the roll it gradually changesthe composition of the glue within the chamber l4 and renders theoperation non-uniform. By providing a bypass constantly returning gluefrom chamber [4 to the reservoir 20, we find that this difficulty can beovercome and that a body of glue, uniform throughout the entireglue-drying operation, can be maintained within container I4.

Directly above the applying roll is is supported an air pipe 2? havingupwardly-extending spaced openings 28 engaging a forwardly-turned baffie29. Compressed air, discharged through pipe 27 and merged into acontinuous fluid stream by the baflie 29, engages the body of glue whichhas just been subjected to the heatof roll i8 and cools it and supportsit upon the roll It. By this means,

a heavier film is maintained upon the roll it, and

the production of the apparatus considerably increased. To the rear ofthe compressed air pipe 27, we provide the blowers 39 which direct aheavy stream of air against the glue film on the ascending side of theroll Hi. At this point, the roll of glue film is in substantially avertical position and, where it contains considerable moisture, the airblast serves as a physical support for the glue, maintaining it againstthe roll it.

Any suitable means for removing the glue film to form a glue sheet maybe provided. In the illustration given, we provide a knife 3! carried bya pivoted crank arm 32 which in turn is actuated by a threaded member 33mounted in bracket 32%. Below the knife 3|, we provide a pipe 34 havingopenings 35 directed upwardly and adapted to discharge steam against theedge of the knife and the underside of the glue sheet 36 as it leavesthe roll 10.

On the opposite side of the sheet 36 from the steam pipe 34, we providea pair of pipes 37 and 38. The pipe 3? has airports 39 for directingstreams of compressed air toward the point of the knife so as to causeit to impinge on the outer side of the sheet 35 as it leaves the roll.Here, the air has a surface-hardening and/or skinning effect, giving theouter surface of the glue sheet 36 a tough skin which serves as a meansfor supporting the sheet leaving the roll. Since the sheet is no longerheated by the roll at this point, the effect of the air is instantaneousin forming the strengthening film along the outer side of the sheet. Ifdesired, a secondary blast of air may be directed from pipe 38 throughthe ports 49 upon the sheet 36 just before it passes between thechilling rolls.

. Mounted below the knife 3! and with their faces almost contacting at aline to the left of the knife 3! are the chiliing rollers 4i and 42. Therollers are driven toward each other so as to draw the sheet 36downwardly between them and toward the conveyor apparatus. It isdesirable to have the entire glue sheet adhere at all times to but oneof the brine-cooled chill rolls. This is facilitated by employing rollswith different metal surfaces. For example, the roll 4! ischromium-plated and it is found that the glue sheet does not adhere tothe chromium-surfaced roll. The roll 42 is a steel roll and ispreferably operated at a lower temperature than the chromium-surfacedroll. With this arrangement, the glue sheet adheres entirely to thesteel roll. As shown more clearly in Fig. 4, an adjustable knife 43 iseffective in stripping the glue sheet and frost away from the roll 42,and the single knife is sufficient for this purpose. If desired,however,

4 each of the rolls 4| and 42 may be supplied with a doctor knife. Theknife 44 for the roll 4| is ordinarily not used and tension is notsupplied thereto because there is very seldom any occasion for scrapingglue from the roll. The arrangement of the rolls so as to draw the gluesheet downwardly and forwardly further enhances the effectiveness of therolls in causing the sheet to adhere solely to the roll 42.

Below the roll 42 extends an endless conveyor 45 which extends upwardlyand forwardly through the first pass of the apron drier 46. The conveyorbelt is constructed of galvanized T-bar girts 4? spaced at three inchintervals, the girts being arranged in inverted T-shape, as indicatedbest in Fig. 4. With the arrangement shown, the outer or dry side of theglue sheet is deposited upon the outer ends of the girts, while theinner or wet side of the sheet makes no contact with the conveyor. Thelinear speed of the conveyor is preferably adjusted to equal theperipheral speed of the chill rollers 4| and 42.

The drier may be of any suitable type or construction. In theillustration given, the casing provide in addition to the apron driercompartment 45, an intermediate compartment 48 and a lower compartment49. Endless conveyors 45 are provided in each of the compartments toprovide three passes in each tier. Air circulation fans 50 are employed,and steam-heating coils 5| are provided for supplying the necessaryheat. If desired, the last two conveyors in the lower compartment 49 maybe bypassed by bringing the glue sheet 36 directly upon the outletconveyor r 52. Conveyor 52 discharges the glue onto a breaker wheel 53of well-known construction. The broken or fragmented product falls intothe outlet chute 54.

We have found that very effective results for the comminuting operationare brought about by discharging a blast of air by means of the fan 55supported directly above conveyor 52 so that a final surface drying isaccomplished by the air fan 55 just before the comminuting step. The useof such a fan, however, is not essential to method of preparation.

Any suitable temperatures in the drier may be employed. As an example,the top compartment 45, where the sheet enters, may be operated in thelow temperature range of F. to F. to prevent melting; the middle tier 48may be operated at a temperature range of F. to F; while the bottomcompartment 49 may use temperatures ranging from 125 F. to F. It will beunderstood that these conditions are changed depending upon the type ofglue being dried. In the handling of certain types of glues, it is foundthat no heat need be used in any of the tiers of the drier. It is notnecessary that the air used in the drier be conditioned with respect tohumidity.

We find that the T-bar girts on the conveyor 45 in the middlecompartment 48 may be spaced more widely apart, if desired, say at sixinch intervals. The conveyors 45 in each of the compartments of thedryer may be similar and, if desired, the last two conveyors may beconstructed of wire screening.

As the glue sheet 35 leaves compartment 49, the cooling fan 55 impingesa blast of air upon the sheet, and such blast is highly effective whenthe glue sheet is very thick. Should the lue sheet be thin, the fan 55need not be used.

In the specific illustration given, the nine-foot diameter steam drum orroll I0 is rotated in the escapes direction of the arrow shown in Fig.1, and at a speed of about .75 R. P. M., while the chill rolls (16inches in diameter) rotate at about 2 R. P. M. Thus, the peripheralspeed of the drum is two and one-half times greaterthan the peripheralspeed of the chill rolls, and we prefer that the peripheral speed of thedrying roll exceed the peripheral speed of the chill rolls for thereason which will now be set out. The greater peripheral speed of theroll, coupled with the lower peripheral speed of the chilly rolls,cooperates in the forming of a crinkled or corrugated sheet of glueleaving the roll it. The crinkled or corrugated sheet is illustrated inFigs. 2 and 3.

The glue sheet, as it leaves the roll 10', tends to overlap itself andto form the irregular corrugations and crinkles illustrated in Figs. 2and 3 and, in the subsequent drying operation, these crinkles persistand are of great value, both in the drying process and in the finalproduct. In the drying process, the loops and bends ,or crinkles,illustrated best in Fig. 3, are highly effective in preventing the gluesheet from sticking to the conveyor, while at the same time permitting acirculation of air completely around the crinkled sheet. In the finalproduct, the irregular or crinkled shape persists in the brokenup orcomminuted material and aids greatly in causing the glue to dissolve ina water body. A mass of such fragmented glue when placed within a waterbody permits the water to pass quickly through the material and todissolve the flakes. As indicated best in Fig. 3, the sheet 36 hasspaced peaks or ridges 56 and corresponding hollows or recesses 51.

Operation In the operation of the process and apparatus, glue (or anyother gelatin body) is supplied from the reservoir 20 to the containerIt, We have found that best results are obtained by using a feed liquorconcentration ranging from 16% to 38% solids (84% to 62% moisture). Theconcentration used depends greatly upon the test and viscosity of thetype of glue being dried. For example, lower test bone, chrome, andfleshing glues may be operated in the range of 28% to 38% solids, whilethe higher test hide glues may be fed in a concentration of 16% to 28%solids. Feed temperatures may vary from 110 F. for very low test gluesto 130 F. for high test glues.

The feed or applicator roll I5 may be heated with steam or cooled withwater to aid in temperature control. The roll is preferably equippedwith adjustable bearings Is in order that the clearance between the rolland steam drum may be varied, this clearance determining to a certainextent the thicknes and uniformity of the glue.

The temperature of the steam-heated roll or drum It may be variedwidely. We find that excellent results are obtained when the interiortemperature of the steam-heated drum is about 230 F. (the temperature ofsaturated steam at a gauge pressure of six pounds per square inch). Wehave obtained good results with steam pressures of from five to tenpounds per square inch.

The applicator roll I 5 picks up a surface covering a glue and depositsit as a film l6 upon the roll l0. Compressed air is directed by the pipe21 and deflector 29 upon the film [6 to aid in smoothing out the filmand thus providing a more uniform application. The air streams emittedthrough the ports 28 of the pipe 21 are 6 merged in a continuous thinsheet by the bafile 29.

The blowers 30 impinge air on the drum so as to produce a smoothing ofthe glue film while also holding the glue upon the heated drum. Such airis extremely useful in holding glues with a grease content on the heateddrum. The smoothing action of the air causes the flexible sheet to havefewer spots as might :be produced by uneven application, hence producinga more uniform product. Further, the blower air hastens the drying ofthe glue on the drum. The blower air may be unconditioned and employedat room temperature of from F. to F.

The rate of rotation of the steam drum or roll ii] may be varied.Excellent results have been obtained at from .75 to 1.25 R. P. M., withan internal steam pressure of 5 to 9 pounds per square inch.

The relatively high peripheral speed of the roll it in conjunction withthe lower peripheral speed of the rollers 41 and 52 produced inconjunction with the doctor knife 3! a crinkling of the film as it formsthe glue sheet 38. At the same time, the discharge of compressed airthrough pipe 31 overcomes any weakness in the product which might beproduced by such crinkling and forms a skin or hardened surface on theouter side of the sheet 36, enabling the sheet to be supported byitself. The primary air pipe 3'! directs the air streams at the cuttingedge of the steam drum knife. At this point, the glue has been dried onthe film to a highly Viscous fluid. As the compressed air streamscontact the fluid glue at the knife, a skinning or surface-hardeningeffect takes place, imparting sufficient strength to enable the glue tobe drawn down in a continuous sheet by the chill rolls 4i and 42. Pipe38 provides merely an auxiliary supply of air to aid the primary air inthe Skinning process.

Steam, particularly during the starting up of the operation, may beintroduced through the steam line 3 to direct steam at the cutting. edgeof the knife 3 1. During continuous operation, it is found not to benecessary to use th steam, but its use is found desirable when startingthe formation of the sheet.

The moisture content of the sheet being removed from the roll may rangefrom 12% to 30%, but we prefer to take off the glue when its moisturecontent is from 17% to 24%. A higher moisture than 30% causes the sheetto adhere to the conveyor, While a dryer sheet is not conducive to aconsistent operation. The sheet thickness varies from ,4 inch to /32inch, depending upon the chill roll speed used in operation.

The chill rolls are operated to provide a peripheral speed substantiallyless than the peripheral speed of the drying roll iii. Preferably, theratio of the peripheral speed of the drying roll to that of a chillingroll is 2 /4 to 1 up to 2% to 1. Excellent results are obtained when theratio is 2 /2 to 1. Such unequal speeds result in a doubling up of thefilm in the formation of the sheet, giving a rippled or crinkled effect.

The glue sheet 35 does not tend to adhere to the chromium-surfacedroller M, but does cling to the steel rollers 42, as indicated in Fig.4, and the knife 43 is eifective in removing the glue and the innerfrost coating thereof from the chilling roller 42.

The outside or dryer side of the glue sheet is allowed to rest againstthe girts 41 of th endless conveyor 45. Thus, the dry side of the glue,combined with the spaced girts 41, and the crinkled character of theglue sheet 36 itself, all cooperate in minimizing the tendency of thefilm 36 to stick to the conveyor. Uniform results can be obtainedbecause the glue sheet 36 can remain plastic, containing a substantialamount of moisture, thus permitting a uniform sheet-forming and dryingoperation.

The glue is carried through the apron drier where it may be subjected toheat and air, and finally the sheet is drawn onto the outlet conveyor52. Here, if the sheet is thick, it is subjected to a blast of roomtemperature air from fan 55 before being broken up by the wheel 53. Thebreaker 53 breaks the flakes into an average particle size of from onesquare inch to any desired size. The final moisture content is about 12%which is considered as commercial dry glue. From this point, the flakescan be ground in any regular mill to the degree desired by the user.

While in the foregoing specification, we have described the invention inconsiderable detail, both as to steps and apparatus, for the purpose ofillustrating one embodiment of the invention,

it will be understood that such details may be varied widely by thoseskilled in the art without departing from the spirit of our invention.

We claim:

1. In apparatus for the film drying of glue, a frame, a drying rollrotatably mounted in said frame, means for heating said drying roll,means for supplying a film of glue to the roll, a scraper for removingthe film as a sheet of glue from said drying roll, a pair of chillingrolls rotatably mounted in said frame, one of said chilling rolls havinga surface to which said sheet does not adhere while the other of saidchilling rolls has a surface to which the sheet tends to adhere, andpower means having connections with said rolls for rotating said dryingroll at a greater peripheral speed than the peripheral speed of saidchilling rolls.

2. The apparatus of claim 1 in which one of the chilling rolls ischromium-surfaced while the other roll has a steel surface.

3. In a process for drying glue in sheet form, the steps of applyingglue in a film upon a heated rotating roll, scraping the film away fromthe roll to form a sheet, and passing the sheet between two tensionrolls while rotating the tension rolls at a slower peripheral speed thanthe heated roll whereby said sheet under said scraping action iscrinkled as it leaves said roll.

4. In a process for drying glue in sheet form, the steps of applyingglue in the form of a film to a heated rotating roll, scraping the rollto free the film when partially dried from said roll and to form a gluesheet, passing the sheet between chilled rollers, and rotating thedrying roll at a peripheral speed greater than the speed of the chilledrolls whereby said sheet under said scraping action is crinkled as itleaves said roll.

5. In a process for drying glue in sheet form, the steps of applyingglue to a heated rotating roller to form a film thereon, scraping theroll to free'the film when partially dried from said roll and to form aglue sheet, and passing the sheet between tension rolls at a slowerperipheral speed than the heated roll; whereby said sheet under saidscraping action is crinkled as it leaves said heated roll, said heatedroll being rotated at a peripheral speed bearing ratio to the peripheralspeed of the tension rolls of from 2 to 1 to 2% to 1.

ALBERT H. ZEIGLER. CHARLES M. HARRIS, JR.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,318,464 Schweizer Oct. 14, 19191,582,604 Hopkinson Apr. 27, 1926 1,583,484 Morrison May 4, 19261,746,751 Van Derhoef Feb. 11, 1930 2,140,788 Cowgill Dec. 20, 1938

